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glsl: Compare vector indices in blocks

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Just like the non-constant array index lowering pass, compare all N
indices at once.  For accesses to a vec4, this saves 3 comparison
instructions on a vector architecture.

Reviewed-by: Eric Anholt <eric@anholt.net>
This commit is contained in:
Ian Romanick 2011-07-18 18:51:25 -07:00
parent 90cc372400
commit 6c8f1f483a
1 changed files with 39 additions and 23 deletions
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62
src/glsl/lower_vec_index_to_cond_assign.cpp
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@ -71,8 +71,6 @@ ir_vec_index_to_cond_assign_visitor::convert_vec_index_to_cond_assign(ir_rvalue
ir_assignment *assign;
ir_variable *index, *var;
ir_dereference *deref;
ir_expression *condition;
ir_swizzle *swizzle;
int i;
if (!orig_deref)
@ -86,39 +84,52 @@ ir_vec_index_to_cond_assign_visitor::convert_vec_index_to_cond_assign(ir_rvalue
assert(orig_deref->array_index->type->base_type == GLSL_TYPE_INT);
exec_list list;
/* Store the index to a temporary to avoid reusing its tree. */
index = new(base_ir) ir_variable(glsl_type::int_type,
"vec_index_tmp_i",
ir_var_temporary);
base_ir->insert_before(index);
list.push_tail(index);
deref = new(base_ir) ir_dereference_variable(index);
assign = new(base_ir) ir_assignment(deref, orig_deref->array_index, NULL);
base_ir->insert_before(assign);
list.push_tail(assign);
/* Temporary where we store whichever value we swizzle out. */
var = new(base_ir) ir_variable(ir->type, "vec_index_tmp_v",
ir_var_temporary);
base_ir->insert_before(var);
list.push_tail(var);
/* Generate a single comparison condition "mask" for all of the components
* in the vector.
*/
ir_rvalue *const cond_deref =
compare_index_block(&list, index, 0,
orig_deref->array->type->vector_elements,
mem_ctx);
/* Generate a conditional move of each vector element to the temp. */
for (i = 0; i < orig_deref->array->type->vector_elements; i++) {
deref = new(base_ir) ir_dereference_variable(index);
condition = new(base_ir) ir_expression(ir_binop_equal,
glsl_type::bool_type,
deref,
new(base_ir) ir_constant(i));
ir_rvalue *condition_swizzle =
new(base_ir) ir_swizzle(cond_deref->clone(ir, NULL), i, 0, 0, 0, 1);
/* Just clone the rest of the deref chain when trying to get at the
* underlying variable.
*/
swizzle = new(base_ir) ir_swizzle(orig_deref->array->clone(mem_ctx, NULL),
i, 0, 0, 0, 1);
ir_rvalue *swizzle =
new(base_ir) ir_swizzle(orig_deref->array->clone(mem_ctx, NULL),
i, 0, 0, 0, 1);
deref = new(base_ir) ir_dereference_variable(var);
assign = new(base_ir) ir_assignment(deref, swizzle, condition);
base_ir->insert_before(assign);
assign = new(base_ir) ir_assignment(deref, swizzle, condition_swizzle);
list.push_tail(assign);
}
/* Put all of the new instructions in the IR stream before the old
* instruction.
*/
base_ir->insert_before(&list);
this->progress = true;
return new(base_ir) ir_dereference_variable(var);
}
@ -189,24 +200,29 @@ ir_vec_index_to_cond_assign_visitor::visit_leave(ir_assignment *ir)
assign = new(ir) ir_assignment(deref, ir->rhs, NULL);
list.push_tail(assign);
/* Generate a single comparison condition "mask" for all of the components
* in the vector.
*/
ir_rvalue *const cond_deref =
compare_index_block(&list, index, 0,
orig_deref->array->type->vector_elements,
mem_ctx);
/* Generate a conditional move of each vector element to the temp. */
for (i = 0; i < orig_deref->array->type->vector_elements; i++) {
ir_rvalue *condition, *swizzle;
ir_rvalue *condition_swizzle =
new(ir) ir_swizzle(cond_deref->clone(ir, NULL), i, 0, 0, 0, 1);
deref = new(ir) ir_dereference_variable(index);
condition = new(ir) ir_expression(ir_binop_equal,
glsl_type::bool_type,
deref,
new(ir) ir_constant(i));
/* Just clone the rest of the deref chain when trying to get at the
* underlying variable.
*/
swizzle = new(ir) ir_swizzle(orig_deref->array->clone(mem_ctx, NULL),
i, 0, 0, 0, 1);
ir_rvalue *swizzle =
new(ir) ir_swizzle(orig_deref->array->clone(mem_ctx, NULL),
i, 0, 0, 0, 1);
deref = new(ir) ir_dereference_variable(var);
assign = new(ir) ir_assignment(swizzle, deref, condition);
assign = new(ir) ir_assignment(swizzle, deref, condition_swizzle);
list.push_tail(assign);
}